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Finding a fast SD card for the Raspberry Pi

I wanted to find the fastest SD card for my Raspberry Pi, or at least one that wasn’t so slow that it was going to cause a bottleneck. There are a few threads on the raspberrypi.org forums about performance benchmarks. The prevailing opinion on the “SD Card Benchmarks” thread at raspberrypi.org is that the SanDisk Ultra SDHC 8 GB Class 6 cards have perhaps the best random read/write speeds, which people feel is a good, if theoretical, metric for how the Raspberry Pi will access the card. But at least one Raspberry Pi owner who had done some of the benchmarking that suggested SanDisk Ultra cards would be ideal discovered that the board would not boot from the card.

Of the Class 4 SanDisk Ultra cards, SanDisk Ultra 4GB SDHC Class 4 Flash Memory Card SDSDH-004G-U46 is reported to work, but it requires that the power be disconnected and the card allowed to sit for a minute or two before it will reboot. That may be acceptable for a use case where the Raspberry Pi is sitting on my desk, but not one where it will be tucked behind other equipment.

I happened to be near a Walmart over the weekend, so I stopped in and picked up a SanDisk 4GB SDHC Class 4 Flash Memory Card SDSDB-4096-AW11. I benchmarked it with CrystalDiskMark, and found it to underperform my target of random write speeds of 1 MB/s.